This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ33100: ACC, Coulomb Counting

Part Number: BQ33100
Other Parts Discussed in Thread: BQ35100, BQSTUDIO

I am using four BQ35100 in ACC mode to monitor the capacity of fours battery packs. The batteries are primary cells. They are connected in parallel and each battery pack has a diode inline to prevent one pack to discharge into another one. When we turn ON the load, the Fuel gauges are reporting the amount of coulomb that is delivered to the load. When we turn OFF the load for like one hour, we noticed the coulomb count for one of the fuel gauges decreased. Could you please give us some explanation on why the coulomb count is decreasing for one of the fuel gauges?

  • Hello Justin,

    I have assigned this to our device expert.

    For this issue, can you provide a bqStudio log showing this behavior?

  • Log_20200514_121436.txt
    Turn ON the 100mA load for 1 minute and measured the coulomb delivered to the load
    
    Fuel Gauge A
    20200514_121901.642  WRITE 55 02
    20200514_121901.645  READ 55 62FEFFFF   Coulomb count= 414�Ah
    Fuel Gauge B
    20200514_121901.658  WRITE 55 02
    20200514_121901.661  READ 55 70FEFFFF   Coulomb Count =400�Ah
    Fuel Gauge C
    20200514_121901.674  WRITE 55 02
    20200514_121901.676  READ 55 51FEFFFF   Coulomb Count = 431�Ah
    Fuel Gauge D
    20200514_121901.689  WRITE 55 02
    20200514_121901.692  READ 55 45FEFFFF   Coulomb Count = 443�Ah
    
    
    Wait for 1 hour and and measure the coulomb again
    
    Fuel Gauge A
    20200514_132240.962  WRITE 55 02
    20200514_132240.965  READ 55 55FEFFFF   Coulomb Count = 427�Ah
    Fuel Gauge B
    20200514_132240.978  WRITE 55 02
    20200514_132240.981  READ 55 7CFEFFFF   Coulomb Count = 388�Ah
    Fuel Gauge C
    20200514_132240.994  WRITE 55 02
    20200514_132240.997  READ 55 F9FDFFFF   Coulomb Count = 519�Ah
    Fuel Gauge D
    20200514_132241.010  WRITE 55 02
    20200514_132241.013  READ 55 4DFEFFFF   Coulomb Count = 435�Ah
    
    
    

  • Hello Kang,
    Attached is the log file. The coulomb count is changing a little bit with no load connected.

  • Justin,

    Have you measured the voltage across the senseR to verify there is a 0V drop? The amount of charge you are seeing is possible to be noise. When there is no current flowing we would expect the bq35100 to be off to save power. This is because the power of the bq35100 is not measured. 

    Thanks,

    Eric Vos